Field of the Invention
The invention relates to a fan wheel, in particular for propelling cooling air, in particular for an internal combustion engine, comprising a hub on which a plurality of fan blades is arranged and whereby the hub has a rib structure.
Description of the Background Art
So-called visco fans for engine cooling are fastened by means of a fluid friction coupling, a so-called visco coupling, to the crankshaft of the internal combustion engine and supply the internal combustion engine with air for cooling. Vibrations of the internal combustion engine are therefore transmitted via the coupling to the fan. The fan therefore experiences strong vibration excitations in all directions, both as axial displacements but also in the form of tilting.
A rotor for a semi-axially operating fan, which has a hub on which a plurality of fan blades is arranged, is known from DE 41 17 342 C1. The hub of the fan is provided with a hub ramp, which is arranged upwardly inclined on the outer side of the hub. The hub itself is provided with hollow spaces, which are separated from one another by radially extending webs. In this open hub structure, the fan blades merge directly into the flat hub.
DE 100 05 857 A1 discloses a blade wheel, in particular for a blower unit, in which the hub comprises a substantially ring-shaped wall, which is centered on the axis of rotation of the blade wheel. The blades are connected to a circumferential outer surface, which delimits the ring-shaped wall of the hub. The peripheral surface in this case comprises two zones, separated axially by the blades.
U.S. Pat. No. 6,375,427 B1 discloses a fan for cooling an internal combustion engine, which has a hub structure formed as an auxiliary structure. This hub structure has both radially extending and also diagonally and crosswise extending webs to increase the fan stability.
A hub structure of this kind is very expensive in terms of production and is not always sufficient to cancel out the vibrations of the internal combustion engine, which cause a strong excitation in the tilting and bending direction of the fan.